1. Field of the Invention
Exemplary embodiments of the present invention relate to a liquid crystal display (LCD).
2. Description of the Related Art
Liquid crystal displays (LCDs) are one of the most widely used type of flat panel displays. Generally, an LCD includes a pair of display panels having electrodes, and a liquid crystal layer interposed between the display panels. An LCD displays a desired image by is applying voltages to the electrodes, to rearrange liquid crystal molecules of the liquid crystal layer, to thereby control the amount of light that passes through the liquid crystal layer.
Specifically, an LCD includes: an upper display panel having a common electrode, color filters, a black matrix, etc.; a lower display panel having thin-film transistors (TFTs), pixel electrodes, etc.; and a liquid crystal material having an anisotropic dielectric constant and that is injected between the upper and lower display panels. In the LCD, different electric potentials are applied to the pixel electrodes and the common electrode to adjust the intensity of an electric field formed in the liquid crystal material. Accordingly, the molecular arrangement of the liquid crystal material is changed, thereby controlling the amount of light that passes through a transparent insulating substrate. As a result, a desired image is displayed on the LCD.
A lower display panel includes gate lines transmitting scanning signals, data lines transmitting image signals, TFTs connected to the gate lines and the data lines, and pixel electrodes connected to the TFTs, respectively. The gate lines intersect the data lines to define a plurality of pixels, and the TFTs are provided in each of the pixels, respectively. A TFT includes a gate electrode that is part of a gate line, a semiconductor layer that forms a channel, a source electrode that is part of a data line, a drain electrode, and the like. A TFT is a switching element that selectively allows an image signal received from a data line to be transmitted to a pixel electrode, in response to a scanning signal received from a gate line.
Recently, transparent display devices have been developed that can be operated with a low power consumption and that provide improved aesthetic design. An image projected onto such a transparent display device is viewable simultaneously from opposing sides of the display device.
Of various transparent display devices, a display device using an organic light-emitting diode (OLED) has a transmittance of 30 to 40%. Further, an image is viewable from both directions of the display device, and an object located behind the display device is viewable. Unlike other display devices including OLED displays, LCDs generally cannot be implemented as transparent displays, due to their low transmittance.